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PDF WM8728 Data sheet ( Hoja de datos )
| Número de pieza | WM8728 | |
| Descripción | 24-bit/ 192kHz Stereo DAC with Volume Control and DSD Support | |
| Fabricantes | Wolfson Microelectronics plc | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de WM8728 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
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WM8728
24-bit, 192kHz Stereo DAC
with Volume Control and DSD Support
DESCRIPTION
The WM8728 is a high performance stereo DAC designed
for audio applications such as DVD, home theatre systems,
and digital TV. The WM8728 supports PCM data input word
lengths from 16 to 32-bits and sampling rates up to 192kHz.
Alternatively the WM8728 can operate in DSD compatible
mode where a 64x bitstream is input for each channel. The
WM8728 consists of a serial interface port, digital
interpolation filters, multi-bit sigma delta modulators and
stereo DAC in a small 20-pin SSOP package. The WM8728
also includes a digitally controllable mute and attenuate
function for each channel.
The WM8728 supports a variety of connection schemes for
audio DAC control. The 2 or 3-wire MPU serial port provides
access to a wide range of features including on-chip mute,
attenuation and phase reversal. A hardware controllable
interface is also available (DSD operation is only possible in
hardware mode).
The WM8728 is an ideal device to interface to AC-3,
DTS, and MPEG audio decoders for surround sound
applications, or for use in DVD players supporting DVD-A.
BLOCK DIAGRAM
Product Preview, Rev 1.2, April 2001
FEATURES
• Stereo DAC with 24 bit PCM or single bit DSD operation
• Audio Performance
- 106dB SNR (‘A’ weighted @ 48kHz) DAC
- -97dB THD
• DAC Sampling Frequency: 8kHz - 192kHz
• 2 or 3-Wire Serial Control Interface or Hardware Control
• Programmable Audio Data Interface Modes
- I2S, Left, Right Justified, DSP
- 16/20/24/32 bit Word Lengths
• Independent Digital Volume Control on Each Channel with
127.5dB Range in 0.5dB Steps
• 3.0V - 5.5V Supply Operation
• 20-pin SSOP Package
• Exceeds Dolby Class A Performance Requirements
APPLICATIONS
• DVD-Audio and DVD ‘Universal’ Players
• Home theatre systems
• Digital TV
• Digital broadcast receivers
MODE LATI2S SCKDSD SDIDEM MUTEB CSBIWL ZERO
BCKIN
LRCIN
DIN
SERIAL
INTERFACE
MUTE/
ATTEN
MUTE/
ATTEN
CONTROL INTERFACE
WM8728
PCM/DSD
DIGITAL FILTERS
SIGMA
DELTA
MODULATOR
MUX
RIGHT
DAC
SIGMA
DELTA
MODULATOR
MUX
LEFT
DAC
LOW
PASS
FILTER
LOW
PASS
FILTER
VOUTR
VOUTL
VMID
MCLK
AVDD DVDD
WOLFSON MICROELECTRONICS LTD
Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK
Tel: +44 (0) 131 667 9386
Fax: +44 (0) 131 667 5176
Email: [email protected]
www.wolfsonmicro.com
VREFP VREFN AGND DGND
Product Preview data sheets contain
specifications for products in the
formative phase of development. These
products may be changed or discontinued
without notice.
2001 Wolfson Microelectronics Ltd.
1 page  
WM8728
Product Preview
Test Conditions
AVDD, DVDD = 5V, AGND = 0V, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated.
PARAMETER
SYMBOL TEST CONDITIONS
MIN
TYP MAX
Minimum resistance load
To midrail or a.c.
coupled
1
To midrail or a.c.
coupled
(AVDD = 3.3V)
600
Maximum capacitance load
5V or 3.3V
100
Output d.c. level
(VREFP -
VREFN)/2
Power On Reset (POR)
POR threshold
2.4
UNIT
kohms
ohms
pF
V
V
Notes:
1. Ratio of output level with 1kHz full scale input, to the output level with all ZEROS into the digital input, over a 20Hz to
20kHz bandwidth.
2. All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use such a
filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical
Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic specification
values.
3. VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).
TERMINOLOGY
1. Signal-to-noise ratio (dB) - SNR is a measure of the difference in level between the full-scale output and the output with a
ZERO signal applied. (No Auto-ZERO or Automute function is employed in achieving these results).
2. Dynamic range (dB) - DNR is a measure of the difference between the highest and lowest portions of a signal. Normally a
THD+N measurement at 60dB below full scale. The measured signal is then corrected by adding the 60dB to it. (e.g.
THD+N @ -60dB= -32dB, DR= 92dB).
3. THD+N (dB) - THD+N is a ratio, of the rms values, of (Noise + Distortion)/Signal.
4. Stop band attenuation (dB) - Is the degree to which the frequency spectrum is attenuated (outside audio band).
5. Channel Separation (dB) - Also known as Cross Talk. This is a measure of the amount one channel is isolated from the
other. Normally measured by sending a full-scale signal down one channel and measuring the other.
WOLFSON MICROELECTRONICS LTD
PP Rev 1.2 April 2001
5
5 Page 
WM8728
Product Preview
DEVICE DESCRIPTION
INTRODUCTION
The WM8728 is a high performance DAC designed for digital consumer audio applications. Its
range of features makes it ideally suited for use in DVD players, AV receivers and other high-end
consumer audio equipment.
WM8728 is a complete 2-channel stereo audio digital-to-analogue converter, including digital
interpolation filter, multi-bit sigma delta with dither, switched capacitor multi-bit stereo DAC and
output smoothing filters. The WM8728 includes an on-chip digital volume control, configurable
digital audio interface and a 2 or 3 wire MPU control interface. It is fully compatible and an ideal
partner for a range of industry standard microprocessors, controllers and DSPs.
Control of internal functionality of the device is by either hardware control (pin programmed) or
software control (2 or 3-wire serial control interface). The MODE pin selects between hardware
and software control. The software control interface may be asynchronous to the audio data
interface. In which case control data will be re-synchronised to the audio processing internally.
Operation using a master clock of 256fs, 384fs, 512fs or 768fs is provided, selection between
clock rates being automatically controlled in hardware mode, or serial controlled when in software
mode. Sample rates (fs) from less than 8ks/s to 96ks/s are allowed, provided the appropriate
master clock is input. Support is also provided for up to 192ks/s using a master clock of 128fs or
192fs.
The audio data interface supports right justified, left justified and I2S (Philips left justified, one bit
delayed) interface formats along with a highly flexible DSP serial port interface. When in hardware
mode, the three serial interface pins become control pins to allow selection of, input data format
type (I2S or right justified), input word length (20 or 24 bit) and de-emphasis functions.
In DSD mode, a separate bitstream data input pin is required for each of the channels, plus a 64fs
dataclock MCLK. These signals are applied via pins DIN and LRCIN and the signals routed
internally into the DAC circuits, under control of the SCKDSD mode select pin (19) See Figure 3.
Additionally a Phase Modulation scheme is supported, whereby the audio data is transmitted as a
Manchester encoded bitstream. This has the advantage of removing the significant spectral audio
energy from the datastream, minimising digital signal corruption of the analogue outputs. In order
to simplify decoding of this Phase modulated data, a 2x speed clock (BCKIN) is used to sample
the incoming data. See Figure 4.
The device is packaged in a small 20-pin SSOP.
CLOCKING SCHEMES
In a typical digital audio system there is only one central clock source producing a reference clock
to which all audio data processing is synchronised. This clock is often referred to as the audio
system’s Master Clock. The external master system clock can be applied directly through the
MCLK input pin with no software configuration necessary for sample rate selection.
Note that on the WM8728, MCLK is used to derive clocks for the DAC path. The DAC path
consists of DAC sampling clock, DAC digital filter clock and DAC digital audio interface timing. In
a system where there are a number of possible sources for the reference clock it is recommended
that the clock source with the lowest jitter be used to optimise the performance of the DAC.
WM8728 always acts as a slave and requires clocks to be inputs.
WOLFSON MICROELECTRONICS LTD
PP Rev 1.2 April 2001
11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet WM8728.PDF ] | |
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